Generally, in bending of a sheet such as a sheet metal, multiple die stages are attached to a bending machine such as a press brake so as to create a die layout. Each of the die stages has a punch and a die in a set and is capable of working one or more working parts. While moving between the die stages, an operator performs bending by sandwiching and pressurizing each bending portion (bend line) of a workpiece between the punch and the die in the assigned die stage and plastically deforming the portion.
When the bending can be performed by use of the die layout already attached to the machine or a bending machine having a fixed die layout, the bending is performed without changing the die layout or by adding a die stage required.
In conventional automatic die layout creation processing, a die layout is automatically generated in such a way that a plurality of die stages capable of working are created from the part shape based on a bending order, and then are arranged. The background art as described above is disclosed in the following Published Japanese translation of International Publication for Patent applications.    [Patent Document 1] Patent Brochure of Japanese National Publication of Translated Version (Kohyo) No. Hei 9-509618